CrCL rupture is the most common cause of hind limb lameness in dogs, and can precipitate meniscal injury and inevitably incite osteoarthritis (OA) of the stifle (Johnson et al., Vet Comp Orthop Traumatol, 7:56-69, 1994; and Elkins et al., J Am Anim Hosp Assoc 27:533-540, 1991). Adult, large breed dogs (e.g., Rottweilers, Newfoundlands, and American Staffordshire terriers) are most frequently affected by CrCL rupture (Bennett et al., J Small Anim Pract 29:275-297, 1988; Duval et al., J Am Vet Med Assoc, 215(6):811-814, 1999; and Whitehair et al., J Am Vet Med Assoc, 203:1016-1019, 1993). Although the risk for CrCL rupture increases with age, many large breed dogs succumb to this condition in young adulthood. There is a growing body of evidence that cruciate ligament disease in a certain population of dogs is caused by a biologic or inflammatory process that promotes the gradual failure of the cruciate ligament over time.